Messier 98: Edge-On Spiral Galaxy in Coma Berenices

M98 is a long, thin spiral galaxy at the western edge of the Virgo Cluster, the rich field of galaxies that fills the spring sky between Leo and Virgo. It is not bright, but it is easy to locate next to a naked-eye star, and it makes a good first stop on a tour that continues to M99 and M100.

What it is

M98 is a large spiral galaxy tipped almost edge-on to us, so we see its disk as a narrow spindle. It lies about 44 million light-years away, and its 9.5′ length works out to roughly 120,000 light-years, comparable to or larger than the Milky Way. Most galaxies are moving away from us as the universe expands, but M98 is one of a small number that show a blueshift: it is approaching us, because its own motion inside the Virgo Cluster outweighs the general expansion. Its neighbors in the sky, M99 and M100, are part of the same cluster.

When to see it

This is a spring galaxy. It is highest around midnight in late March and in mid to late evening during April and May. From about 40°N it climbs to roughly 65° above the southern horizon. It sits just north of the celestial equator, so it is also visible from the Southern Hemisphere, low in the north; from 35°S it reaches about 40°.

How to find it

Start at Denebola, the star marking the tail of Leo. Look about 6.6° due east for 6 Comae Berenices, a fifth-magnitude star that shows easily in a finder or binoculars. M98 lies just 0.6° west of 6 Comae, close enough to share a low-power field with it. M99 is about 0.8° southeast of the same star, so 6 Comae is a handy signpost for both.

What you will see

Binoculars will not show much: under a very dark sky, large binoculars may reveal a faint sliver, but most observers need a telescope. A 70–100 mm telescope shows a dim, elongated streak running north-northwest to south-southeast, with a slightly brighter middle; from suburban skies it is a struggle. A 200 mm or larger telescope shows a long spindle with a brighter, oval core and some mottling along the disk on good nights. A filter does not help with galaxies; a dark sky and averted vision do.

History

Pierre Méchain discovered M98 on March 15, 1781, during the same search that turned up M99 and M100. Messier added it to his catalog in April 1781 after measuring its position. Later spectra showed that, unlike most galaxies, it is approaching rather than receding.